1. Field of the Invention
The present invention relates to a battery pack used in a variety of electronic devices, and more particularly to the battery pack which has electronics for heating or protecting the battery pack from a detrimental low temperature in a discharge cycle or discharge operation of the battery pack.
2. Description of the Related Art
A battery pack has been widely used as a main power supply in a variety of electronic devices including cellular phones and a like, and constantly improved in order to increase its per charge life as much as possible.
Shown in FIG. 1 is a graph of a conventional battery pack, illustrating its temperature characteristics. In this graph: a horizontal axis represents a battery capacity in a discharge cycle; a vertical axis represents a variation of battery voltage (volts); and, each of three curves denoting ambient temperatures xe2x80x9cxe2x88x9210xc2x0 C.xe2x80x9d, xe2x80x9c0xc2x0 C.xe2x80x9d and xe2x80x9c20xc2x0 C.xe2x80x9d of a battery housed in the battery pack shows the relationship between the battery capacity in discharge cycle and the variation of battery voltage (volts) at each of the ambient temperatures xe2x80x9cxe2x88x9210xc2x0 C.xe2x80x9d, xe2x80x9c0xc2x0 C.xe2x80x9d and xe2x80x9c20xc2x0 C.xe2x80x9d. As is clear from the graph shown in FIG. 1, as the ambient temperature of the battery decreases, the available battery capacity in discharge cycle of the battery pack decreases. This is a problem inherent in the conventional battery pack.
Incidentally, an example of the conventional battery pack is disclosed in Japanese Laid-open Patent Application No. Hei10-284133, which illustrates heating of the battery of the battery pack during only its charging cycle or charging operation for a purpose of improving its charging efficiency when an ambient temperature of the battery of the battery pack is so low as to be out of a moderate temperature range compatible with normal charging operation of the battery. In operation, this conventional battery is heated by a heating element, wherein the heating element is powered from an external battery charger not from the battery itself. In addition, the conventional battery pack disclosed in the Japanese Laid-open Patent Application No. Hei10-284133 does not disclose nor suggest any idea of heating the battery by using its own electric power in its discharge cycle or discharge operation for the purpose of permitting the battery to keep its normal discharge operation effective even when the ambient temperature of the battery is so low as to be out of a moderate temperature range compatible with its normal discharge operation.
In view of the above, it is an object of the present invention to provide a battery pack capable of performing its normal discharge operation even when an ambient temperature of a battery housed in the battery pack is detrimentally low, and thereby preventing the available period of time of an electronic device powered by the battery pack from decreasing due to such detrimentally low ambient temperature.
According to a first aspect of the present invention, there is provided a battery pack including:
the battery serving as a main power supply of an electronic device, the battery being provided with a positive plate and a negative plate;
a control circuit board electrically connected with both the positive plate and the negative plate of the battery;
a heating element for receiving therein the battery, the heating element being electrically connected with the control circuit board to heat and enable the battery to perform its normal discharge operation even when an ambient temperature of the battery is so low as to be out of a moderate temperature range compatible with its normal discharge operation; and
whereby the battery prevents the available period of time of the electronic device from decreasing in use.
In the foregoing, a preferable mode is one that wherein includes:
a lower casing for receiving therein the battery, the heating element and the control circuit board in a condition in which the control circuit board is projected outward from the heating element so that the control circuit board is mounted on a board support base.
In addition to the above, a preferable mode is one that wherein further includes:
an upper casing for covering the battery, the heating element, the control circuit board and the lower casing.
Preferably, the control circuit board in the battery pack of the present invention comprises:
a temperature detecting element for detecting an ambient temperature of the battery to issue a detection signal to the control circuit board;
a switching element for turning ON and OFF the electric power supplied from said battery to said heating element; and
a control circuit for controlling the electric current supplied from the battery to the switching element and to the heating element upon receipt of the detection signal issued from the temperature detecting element.
According to a second aspect of the present invention, there is provided a battery pack including:
a battery serving as a main power supply of an electric device, the battery being provided with a positive plate and a negative plate;
a control circuit board electrically connected with both the positive plate and the negative plate of the battery;
a heating element for receiving the battery therein, the heating element being electrically connected with the control circuit board through a pair of lead wires;
a lower casing for receiving therein the battery, the heating element and the control circuit board in a condition in which the control circuit board is projected outward from the heating element, so that the control circuit board is mounted on a board support base provided with a plurality of terminal output ports; and
an upper casing for covering the battery, the heating element, the lead wires, the control circuit board and the lower casing; and
whereby, even when an ambient temperature of the battery is so low as to be out of a moderate temperature range compatible with its normal discharge operation, said battery is capable of performing its normal discharge operation, and thereby preventing the available period of time of said electronic device powered by said battery from decreasing.
In the foregoing second aspect, a preferable mode is one wherein the control circuit board includes:
a temperature detecting element for detecting an ambient temperature of the battery to issue a detection signal to the control circuit board; and
a switching element for turning ON and OFF the electric power supplied from the battery to the heating element; and
a control circuit for controlling the electric current supplied from the battery to the switching element and to the heating element upon receipt of the detection signal issued from the temperature detecting element.
With the above configuration, the battery is capable of effectively heating the battery, and thereby increasing the temperature of the battery to keep it in a moderate temperature range compatible with its normal discharge operation, which makes it possible for the battery pack to supply a sufficient amount of electric power to the electronic device such as cellular phones or a like for an extended period of time.